Every January, thousands of small business owners across Stanmore, Harrow, Wembley, and Edgware scramble to file their Self-Assessment tax returns before the 31 January deadline. Many of them overpay, underpay, or miss expenses they’re entitled to claim.

This guide is written for local business owners who want to understand the process, and get it right.

Do I Need to File a Self-Assessment Return?

You need to file if any of the following apply to you:

• You’re self-employed or a sole trader
• You’re a company director
• You earn rental income (even from one property)
• You earn over £100,000
• You have untaxed income (e.g. savings interest, dividend income above the allowance)
• You work under the Construction Industry Scheme (CIS) as a subcontractor
• HMRC has written to you asking you to file

If you’re unsure, it’s always worth checking — not filing when you should is a bigger problem than filing unnecessarily.

Key Deadlines to Know

Miss the 31 January deadline and you’ll face an automatic £100 penalty, even if you have no tax to pay or HMRC owes you money.

What Information Do You Need?

Gathering this before you file (or sending it to your accountant) saves time:

• P60 or employment income records (if applicable)
• Self-employment income and expenses
• Any CIS deduction statements
• Rental income and associated costs
• Bank interest and dividend statements
• Pension contributions
• Gift Aid donations
• Any other untaxed income

What Expenses Can Self-Employed People Claim?

This is where most self-employed people leave money on the table. Allowable expenses include:

• Business mileage (or actual vehicle costs if used purely for business)
• Home office costs (using simplified flat rate or actual proportion)
• Equipment, tools, and materials
• Professional subscriptions and software
• Accountancy fees (yes, this fee is itself tax-deductible)
• Advertising and marketing
• Phone and internet (business proportion)
• Training directly related to your trade

What Happens After You File?

HMRC calculates your tax based on your return. If you owe tax, it’s due by 31 January. If you overpaid through CIS deductions, PAYE, or payments on account, HMRC will send you a rebate.

You may also be asked to make “payments on account”, advance payments towards next year’s bill. These are based on the current year’s tax liability and can catch people off guard if they don’t know to expect them.

Why Use a Local Accountant?

Filing online yourself is possible, but there are good reasons to use a professional:

• Accuracy: An accountant catches deductions you didn’t know you were entitled to
• Speed: No form-filling, no HMRC login frustration, you send your records and it gets done
• Peace of mind: Knowing it’s been filed correctly by an HMRC-registered agent
• Fixed fee: You know the cost upfront, no hidden charges

I’m Talha Alvi, Director of Your Tax Help Accountants, an HMRC-registered agent based in Stanmore. I handle Self-Assessment returns for business owners, landlords, and CIS workers across Harrow, Wembley, and Edgware. Fixed monthly fees, direct service, no passing you to juniors.

📧 info@yourtaxhelp.co.uk | 📞 07478 645331 | 020 80504564